If the U.S. doesn't lead, the strongmen win. For them it's easier.

By the time the second World Trade Center tower collapsed on Sept. 11, 2001, the whole world was watching it. We may assume that Vladimir Putin was watching. Mr. Putin, a quick calculator of political realities, would see that someone was going to get hit for this, and hit hard.

He was right of course. The Bush presidency became a war presidency that day, and it pounded and pursued the Islamic fundamentalists of al Qaeda without...